U.S. patent number 4,601,856 [Application Number 06/803,219] was granted by the patent office on 1986-07-22 for method of purifying oleic acid.
This patent grant is currently assigned to Nippon Oil and Fats Company, Limited. Invention is credited to Kenichi Hashimoto, Tadashi Satoh, Masao Suzuki.
United States Patent |
4,601,856 |
Suzuki , et al. |
July 22, 1986 |
Method of purifying oleic acid
Abstract
A method of producing a highly purified oleic acid is disclosed,
which comprises the steps of: (a) separating and removing the
resulting precipitated crystal after the cooling of a solution of
oleic acid containing fatty acid mixture and urea in an organic
solvent; (b) separating the resulting crystallized crystal after
the partial saponification of the organic solvent solution; and (c)
subjecting the crystal to an acid decomposition.
Inventors: |
Suzuki; Masao (Nishinomiya,
JP), Hashimoto; Kenichi (Kobe, JP), Satoh;
Tadashi (Nishinomiya, JP) |
Assignee: |
Nippon Oil and Fats Company,
Limited (Tokyo, JP)
|
Family
ID: |
26099662 |
Appl.
No.: |
06/803,219 |
Filed: |
December 2, 1985 |
Foreign Application Priority Data
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Jun 12, 1984 [JP] |
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59-119170 |
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Current U.S.
Class: |
554/184; 554/188;
554/190; 554/191; 554/195; 554/202; 554/204 |
Current CPC
Class: |
C11C
1/08 (20130101) |
Current International
Class: |
C11C
1/00 (20060101); C11C 1/08 (20060101); C11C
001/08 () |
Field of
Search: |
;260/419 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2611 |
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Mar 1963 |
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JP |
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585152 |
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Dec 1977 |
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SU |
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Other References
Parker et al., "J. Am. Oil Chemists Soc.", vol. XXXIV, No. 1, Jan.
1957, pp. 43-44, Reprint. .
Swern et al., "J. Am. Oil Chemists Soc.", Jan. 1953, pp.
5-7..
|
Primary Examiner: Evans; J. E.
Attorney, Agent or Firm: Parkhurst & Oliff
Claims
What is claimed is:
1. A method of producing oleic acid, comprising the steps of:
(a) dissolving an oleic acid containing fatty acid mixture and urea
in an organic solvent and then cooling them to separate and remove
the resulting precipitated crystal therefrom;
(b) partially saponifying the fatty acid mixture contained in the
organic solvent solution to separate a crystal by crystallization;
and
(c) subjecting the resulting crystal to an acid decomposition.
2. The method according to claim 1, wherein said fatty acid mixture
in the step (a) is selected from hydrolyzates of fats and oils and
commercially available oleic acid.
3. The method according to claim 1, wherein said urea in the step
(a) is used in an amount of 3-50 times the total weight of
saturated fatty acids having a carbon number of not less than 16
and monounsaturated fatty acids higher than oleic acid, which are
contained in said fatty acid mixture.
4. The method according to claim 1, wherein said organic solvent in
the step (a) is used in an amount of 0.5-10 times the weight of
said fatty acid mixture.
5. The method according to claim 1, wherein said cooling in the
step (a) is carried out by cooling down to a temperature of not
more than 30.degree. C.
6. The method according to claim 1, wherein said partial
saponification in the step (b) is carried out by adding alkaline
chemicals.
7. The method according to claim 1, wherein the degree of
saponification in the step (b) is within a range of from 20% of the
oleic acid to 60% of the total of the fatty acid mixture contained
in said organic solvent solution.
8. The method according to claim 6, wherein said alkaline chemicals
are selected from hydroxides and carbonates of lithium, sodium,
potassium and ammonia.
9. The method according to claim 1, wherein said crystallization of
the step (b) is performed repeatedly.
10. The method according to claim 9, wherein said crystallization
is carried out in the presence of a polar solvent or a mixed
solvent thereof.
11. The method according to claim 1, wherein said step (c) is
carried out with an inorganic or organic acid.
12. The method according to claim 11, wherein said inorganic acid
is selected from sulfuric acid, hydrochlonic acid, nitric acid,
phosphoric acid, phosphorous acid, hypophosphorous acid, carbonic
acid and boric acid.
13. The method according to claim 11, wherein said organic acid is
selected from acetic acid, oxalic acid, malonic acid, succinic
acid, malic acid, tartaric acid and citric acid.
14. The method according to claim 1, wherein after said step (c),
the resulting oleic acid is subjected to an adsorbent treatment or
a distillation.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of producing a highly purified
oleic acid from an oleic acid containing fatty acid mixture.
2. Description of the Prior Art
Oleic acid (cis-9-octadecenoic acid) is a typical unsaturated fatty
acid constituting natural fats and oils or biological lipids, which
is a very important substance in industry and biology.
It has been confirmed recently that highly purified oleic acid is
colorless and odorless, excellent in the stability, high in the
safety and has many excellent physical, chemical and physiological
properties. Thus, such an oleic acid is actively and widely applied
to fine chemical fields such as the life science of
pharmaceuticals, cosmetics and foods, bioscience of biosensors and
biosurfactants, electronics for simulation of biological function
and so on as well as for presently developing high
technologies.
However, commercially available oleic acid includes fatty acid
homologues having different carbon numbers and double bond numbers,
and has a purity as low as 60-90%. In addition, commercially
available oleic acid also contains various minor impurities.
Therefore, the commercially available oleic acid is unsatisfactory
in the qualities such as color, odor, stability, safety and the
like and can not adequately develop performances inherent to oleic
acid.
As a method of increasing a purity of the fatty acid, there have
generally been known various methods such as solvent separation,
emulsification separation, urea separation and the like from the
past. Recently, chromatographies using an adsorbent, an ion
exchange resin and the like have been used. However, these methods
are unsuitable in view of separation and refining levels,
production capacity, production cost and the like as an industrial
means for producing highly purified fatty acids.
Moreover, there is a method wherein the purity of oleic acid is
increased by subjecting polyunsaturated fatty acid such as linoleic
acid, linolenic acid or the like to a partial hydrogenation.
However, this method has a problem of producing positional and
geometrical isomers.
As the demand for oleic acid is increased with the diversification
of applications, it becomes important to provide an oleic acid
having high purity and high quality.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to produce a highly
purified oleic acid from a wider variety of starting materials by a
simple process without producing positional and geometrical
isomers.
According to the invention, there is provided a method of producing
oleic acid, comprising the steps of:
(a) dissolving an oleic acid containing fatty acid mixture and urea
in an organic solvent and cooling them to separate and remove the
resulting precipitated crystal therefrom;
(b) partially saponifying the fatty acid mixture contained in the
organic solvent solution to separate a crystal by crystallization;
and
(c) subjecting the resulting crystal to an acid decomposition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to the invention, the step (a) is a step for removing
higher saturated fatty acids having a carbon number of not less
than 16 and monounsaturated fatty acids higher than oleic acid from
the oleic acid containing fatty acid mixture. After step (a), a
small amount of urea inevitably remains in the resulting organic
solvent solution. When the organic solvent solution is subjected to
the step (b), the remaining urea moderately forms an adduct with an
acid salt of oleic acid to produce a hard and light powdery
crystal, so that the crystallized state of the partially saponified
fatty acid mixture is improved to facilitate the filtration of
crystal obtained by crystallization, whereby the removal of
polyunsaturated fatty acids such as linoleic acid and so on,
monounsaturated fatty acids lower than oleic acid, lower saturated
fatty acids and other impurities can be performed efficiently.
Thus, it is possible to produce a highly purified oleic acid.
As the oleic acid containing fatty acid mixture, use may be made of
any mixtures containing oleic acid, an example of which includes
fatty acids and mixtures thereby obtained by hydrolysis of fats and
oils such as olive oil, sesame oil, rice bran oil, soybean oil,
teased oil, camellia oil, corn oil, rapeseed oil, palm oil, peanut
oil, safflower oil, sunflower oil, tallow, lard, chicken oil,
mutton tallow, fish oil and the like. Furthermore, the commercially
available oleic acid containing impurities may be used as the
starting material. Since the significance of the starting material
is dependent upon the separation effect of impurities according to
the invention, the starting material having a higher oleic acid
content is generally advantageous, but the selection of the
starting material is determined by the objective purity and quality
of oleic acid and the kind and amount of impurities in the starting
material.
As the organic solvent used in the step (a), use may be made of
lower alcohols such as methanol, ethanol, n-propanol, isopropanol
and the like and a mixed solvent consisting mainly of such a lower
alcohol. The amount of the organic solvent used can not absolutely
be determined in accordance with the composition of the starting
fatty acids, objective purity and yield, set of crystallization
number and the like, but is preferably 0.5-10 times the weight of
the starting fatty acids. When the amount of the organic solvent is
less than 0.5 times by weight, the separation effect lowers, while
when it exceeds 10 times by weight, the concentration of fatty acid
lowers and the production efficiency reduces unfavorably.
The amount of urea used is determined by the composition of the
starting fatty acids, objective purity and yield, crystallization
temperature, amount of solvent and the like. Preferably, the amount
of urea used is 3-50 times the total weight of saturated fatty
acids having a carbon number of not less than 16 and
monounsaturated fatty acids higher than oleic acid, which are
contained in the starting fatty acids. When the amount of urea is
less than 3 times by weight, the removal of saturated fatty acids
and higher monounsaturated fatty acids is insufficient, while when
it exceeds 50 times by weight, the yield of oleic acid lowers.
In the step (a), urea and oleic acid containing fatty acid mixture
are dissolved in the organic solvent by warming and then gradually
cooled down to a temperature of not more than 30.degree. C.,
preferably within a temperature range of 20.degree.
C..about.-20.degree. C. Thus, the saturated fatty acids having a
carbon number of not less than 16 and the monounsaturated fatty
acids higher than oleic acid form crystalline adduct with urea, so
that the resulting crystals are removed by the usual manner such as
filtration, centrifugal separation or the like.
Generally, it is sufficient to perform step (a) a single time.
However, step (a) may be repeated when the removal of the saturated
fatty acids having a carbon number of not less than 16 and the
monounsaturated fatty acids higher than oleic acid is
insufficient.
In step (b), the organic solvent solution of the fatty acid mixture
obtained at the step (a) is first subjected to a partial
saponification by adding alkaline chemicals such as hydroxides,
carbonates and so on of lithium, sodium, potassium, ammonia and the
like. In this way, an acid salt of oleic acid is formed by the
partial saponification, which moderately forms an adduct with a
small amount of urea remaining in the step (a) after the cooling to
make a filterable crystal as a whole, so that the separation from
components such as polyunsaturated fatty acids and so on is easy.
The degree of saponification is within a range of from 20% of the
oleic acid contained therein to 60% of the total of the fatty acid
mixture, preferably from 30% of the oleic acid to 55% of the total
of the fatty acid mixture. When the degree of saponification is
less than 20% of the oleic acid, the yield of the resulting oleic
acid is low, while when it exceeds 60% of the total of the fatty
acid mixture, not only is the separation effect lower, but also the
crystallized state and filtrability are poor, thereby decreasing
the purity of the resulting oleic acid.
The cooling temperaure for crystallizing the acid salt of oleic
acid is 10.degree. C..about.-30.degree. C., preferably 5.degree.
C..about.-20.degree. C. When the cooling temperature is higher than
10.degree. C., the yield of oleic acid lowers, while when it is
lower than -30.degree. C., the purity of oleic acid reduces.
The resulting acid salt crystal of oleic acid is separated from the
solution containing polyunsaturated fatty acid and so on in the
usual manner.
Moreover, the purity can be further increased by repeatedly
subjecting the acid salt crystal of oleic acid to
recrystallizatioin.
As a solvent used in the repeated recrystallization for the acid
salt of oleic acid, mention may be made of polar solvents such as
methanol, ethanol, isopropanol, n-butanol, isobutanol, acetone,
methyl ethyl ketone, diethyl ether, ethyl acetate, acetonitrile and
so on, and a mixed solvent containing such polar solvents. In this
case, the amount of the solvent used is preferably 1-10 times the
weight of the acid salt of oleic acid.
The step (c) is a step wherein the acid salt of oleic acid is
subjected to an acid decomposition by adding an acid to produce
free oleic acid.
As the acid used in the acid decomposition, mention may be made of
inorganic acids such as sulfuric acid, hydrochloric acid, nitric
acid, phosphoric acid, phosphorous acid, hypophosphorous acid,
carbonic acid, boric acid and so on; and organic acids such as
acetic acid, oxalic acid, malonic acid, succinic acid, malic acid,
tartaric acid, citric acid and so on. The amount of the acid used
is not less than an equivalent, preferably not less than 1.2
equivalents to the base forming the acid salt of oleic acid.
After the acid decomposition, the acid for the acid decomposition
remaining in oleic acid is removed by washing with water. In this
washing, the emulsification can be prevented by adding a diluted
aqueous solution of a polybasic acid such as oxalic acid, citric
acid or the like, whereby the acid decomposition for the slight
amount of the remaining acid salt of oleic acid is performed
completely.
Thus, a high purity oleic acid is obtained. Moreover, in order to
remove minor impurities, the resulting oleic acid may be subjected
to an adsorbent treatment or distillation usually used in the
refining of fatty acids.
As an adsorbent used in the adsorbent treatment, mention may be
made of clay, activated clay, activated carbon, silica gel, alumina
gel, silica-alumina gel, ion exchange resin synthetic adsorbent and
so on, which may be used alone or in admixture. The amount of the
adsorbent used in dependent upon the refining degree of oleic acid
and the objective quality, but it is 0.1-5% by weight to oleic
acid. In the adsorbent treatment, the temperature is not less than
the melting point of oleic acid, preferably 30.degree.-80.degree.
C., and the treating time is about 20 minutes to 2 hours.
On the other hand, the distillation is performed under a reduced
pressure in an inert gas atmosphere in the usual manner. In this
case, it is desirable to perform a low temperature distillation
under a higher vacuum.
According to the method of the invention, a highly purified oleic
acid having a high level of qualities such as stability to
oxidation, heat and acidic and basic chemicals, safety to cutaneous
health and so on, which have never been attained in the prior art,
can be obtained from a wide variety of starting materials by a
simple process.
The thus obtained highly purified oleic acid has the following
characteristics:
(i) it is colorless and odorless with a high purity;
(ii) it does not contain minor impurities such as oxidation
products and the like resulting in the degradation of oleic
acid;
(iii) it is excellent in the stability to heat, oxidation and
chemicals;
(iv) it is high in the safety to cutaneous health; and
(v) it has special properties such as sharp polymorphism and the
like.
By utilizing the above mentioned characteristics, oleic acid
obtained according to the method of the invention can widely be
employed in the fine chemical fields such as pharmaceuticals,
cosmetics, biochemicals, electronics and so on as well as presently
developing high technologies.
The following examples are given in illustration of the invention
and are not intended as the limitations thereof. In the examples,
"%" means "% by weight" unless otherwise specified.
EXAMPLE 1
After 1,242 g of urea was added and dissolved into 4,000 g of
methanol under warming at 50.degree. C., 1,000 g of oleic sufflower
oil distilled fatty acid warmed at 50.degree. C. was added and
dissolved thereinto. Next, the resulting solution was cooled from
50.degree. C. to 10.degree. C. with stirring over 4 hours, and the
resulting precipitated crystal was centrifugally filtered off to
obtain 5,212 g of a filtrate (content of fatty acids: 625 g, acid
value: 198.5, content of urea: 232 g). This filtrate was added with
576 g of an aqueous solution containing 41.5 g of sodium hydroxide
(corresponding to 45% of the equivalent of the contained fatty
acid) at 40.degree. C. and cooled to -7.degree. C. with stirring
over 6 hours to obtain 427 g of a crystal of acid salt of oleic
acid (content of acid salt: 370 g) through filtration. The thus
obtained crystal was added with 1,856 g of an aqueous solution
containing 93 g of phosphoric acid (corresponding to 1.5 times the
equivalent of the acid salt) which was subjected to an acid
decomposition with stirring at 90.degree. C. for 2 hours. The thus
obtained oleic acid layer was fully washed with an aqueous solution
of 0.5% citric acid and dehydrated to obtain 356 g of a highly
purified oleic acid (A).
EXAMPLE 2
427 g of the acid salt crystal of oleic acid obtained in the same
manner as in Example 1 was dissolved into 1,280 g of methanol
containing 10% of water under warming at 40.degree. C. and then
cooled to -5.degree. C. with stirring over 5 hours to obtain 357 g
of a crystal through filtration. This crystal was added with 1,690
g of an aqueous solution of 5% phosphoric acid, which was subjected
to an acid decomposition with stirring at 90.degree. C. for 2
hours. The resulting oleic acid layer was fully washed with an
aqueous solution of 0.5% citric acid and dehydrated to obtain 324 g
of a highly purified olefic acid (B).
EXAMPLE 3
The acid salt crystal of oleic acid obtained through
recrystallization in the same manner as in Example 2 was dissolved
into 1,071 g of methanol containing 13% of water under warming at
40.degree. C. and then cooled to -5.degree. C. with stirring over 5
hours to obtain 317 g of a crystal through filtration. This crystal
was added with 1,574 g of an aqueous solution of 5% phosphoric
acid, which was subjected to an acid decomposition with stirring at
90.degree. C. for 2 hours. The resulting oleic acid layer was fully
washed with an aqueous solution of 0.5% citric acid and dehydrated
to obtain 302 g of a highly purified oleic acid (C).
EXAMPLE 4
Each of the highly purified oleic acids of Examples 1-3 was added
to 0.5% of activated carbon, stirred at 50.degree. C. under
nitrogen gas atmosphere for 1 hour and filtered to obtain more
highly purified oleic acids (A1), (B1), and (C1).
EXAMPLE 5
Each of the highly purified oleic acids of Examples 1-3 was
distilled below 220.degree. C. at 1 mmHg while blowing a nitrogen
gas to obtain more highly purified oleic acids (A2), (B2) and
(C2).
The compositions and quality characteristics of the highly purified
oleic acids obtained in Examples 1-5 according to the invention are
shown in the following Table 1 together with those of commercially
available oleic acids (a) and (b) as Comparative Examples.
TABLE 1
__________________________________________________________________________
Present invention Oleic saf- Fatty acids flower oil in filtrate
Example Example Example distilled after urea 1 2 3 Example 4 Test
item fatty acids separation (A) (B) (C) (A1) (B1) (C1)
__________________________________________________________________________
1 Composi- C.sub.14:0 0.1 0.2 tion of C.sub.16:0 4.8 0.2 fatty
C.sub.16:1 0.1 0.2 acids C.sub.18:0 2.3 (%) C.sub.18:1 77.1 78.4
99.2 99.9 more 99.2 99.9 more cis-.omega.9 than than 99.9 99.9
C.sub.18:1 (isomer) C.sub.18:2 14.2 19.8 0.8 0.1 0.8 0.1 C.sub.18:3
0.9 1.2 C.sub.20:0 0.5 others 2 Carbonyl value 5.2 0.4 0.2 0.1 0.2
0.1 0 (meq/kg) 3 Odor intensity 7 1-2 1 0-1 0-1 0 0 4 Original
color 80 20 15 10 5 5 5 (APHA) 5 Heat color 180 60 40 30 15 10 5
stability (APHA) 6 Thermal oxida- 350 80 60 50 40 30 25 tion color
stability (APHA) 7 Base color 400 90 70 50 60 40 30 stability
(APHA) 8 Acid color 450 120 90 70 80 60 50 stability (APHA) 9
Oxidation 22.5 0.1 0 0 0 0 0 stability (POV) 10 Skin positive
almost almost almost nega- nega- nega- irritation nega- nega- nega-
tive tive tive tive tive tive
__________________________________________________________________________
Comparative example Present invention Commercially Commercially
Example 5 available available Test item (A2) (B2) (C2) oleic acid
(a) oleic acid (b)
__________________________________________________________________________
1 Composi- C.sub.14:0 3.1 2.6 tion of C.sub.16:0 4.3 3.6 fatty
C.sub.16:1 7.8 6.4 acids C.sub.18:0 1.4 1.1 (%) C.sub.18:1 99.2
99.9 more 68.0 71.1 cis-.omega.9 than 99.9 C.sub.18:1 (isomer)
C.sub.18:2 0.8 0.1 5.5 0.8 C.sub.18:3 0.6 C.sub.20:0 0.1 others 3.5
3.8 2 Carbonyl value 0.2 0 0 15.6 9.2 (meq/kg) 3 Odor intensity 0-1
0 0 10 8 4 Original color 5 5 0 220 120 (APHA) 5 Heat color 10 5 5
400 280 stability (APHA) 6 Thermal oxida- 40 25 15 .gtoreq.500
.gtoreq.500 tion color stability (APHA) 7 Base color 50 30 20
.gtoreq.500 .gtoreq.500 stability (APHA) 8 Acid color 60 40 30
.gtoreq.500 .gtoreq.500 stability (APHA) 9 Oxidation 0 0 0 26.8 6.2
stability (POV) 10 Skin nega- nega- nega- positive almost
irritation tive tive tive positive
__________________________________________________________________________
The test item 1 shows the composition of fatty acid mixture
measured by a gas chromatography using a capillary column. Oleic
acid is represented by C.sub.18:1 cis-.omega.9.
The test item 2 shows a content (milli equivalent/kg) of carbonyl
compounds as typical minor impurities.
The test item 3 gives an odor index evaluated by an organoleptic
test, wherein odorless is 0 and the odor intensity of the
commercially available oleic acid (a) is 10, respectively.
In the test items 4 to 8, the larger the value of color, the larger
the coloration degree and the poorer the quality.
The test item 5 shows a heat color stability of oleic acid after
heated at 205.degree. C. in a nitrogen stream for 1 hour.
The test item 6 shows a thermal oxidation color stability of oleic
acid after heated at 150.degree. C. in air for 3 hours.
The test item 7 shows a color stability of oleic acid against basic
chemicals after oleic acid is added with an equimolar amount of
diethanolamine and heated at 150.degree. C. for 2 hours while being
stirred with nitrogen gas.
The test item 8 shows a color stability of oleic acid against
acidic chemicals after oleic acid is added with 0.05% of
paratoluenesulfonic acid and heated at 150.degree. C. for 1 hour
while being stirred with nitrogen gas.
The test item 9 shows a peroxide value (milli equivalent/kg) after
oleic acid is heated at 60.degree. C. for 5 hours while being
stirred through aeration (300 ml/min). The larger the value, the
poorer the oxidation stability.
The test item 10 shows a result of skin irritation test according
to Kawai's method [The journal of Dermatology, vol 2, p 19 (1975)],
wherein negative is no irritation, almost negative is weak
irritation, almost positive is middle irritation and positive is
strong irritation. This indicates the safety to cutaneous
health.
EXAMPLE 6
After 1,640 g of urea was added and dissolved into 5,000 g of
methanol under warming at 60.degree. C., 1,000 g of teaseed oil
fatty acids warmed at 60.degree. C. was added and dissolved
thereinto. Next, the resulting solution was cooled from 60.degree.
C. to 8.degree. C. with stirring over 4 hours, and the resulting
precipitated crystal was filtered off to obtain 6,196 g of a
filtrate (content of fatty acid: 512 g, acid value: 192.2, and
content of urea: 225 g). This filtrate was added with 703 g of an
aqueous solution containing 35.1 g of sodium hydroxide
(corresponding to 50% of the equivalent of the contained fatty
acid) at 40.degree. C. and then cooled to -10.degree. C. with
stirring over 6 hours to obtain 418 g of crystals of the acid salt
of oleic acid (content of acid salt: 361 g) through filtration.
This crystal was added with 1,535 g of an aqueous solution of 3%
hydrochloric acid, which was subjected to an acid decomposition
with stirring at 90.degree. C. for 2 hours. The resulting oleic
acid layer was fully washed with an aqueous solution of 0.5% malic
acid and dehydrated to obtain 347 g of a highly purified oleic acid
(D).
EXAMPLE 7
The acid salt crystal of oleic acid obtained in the same manner as
in Example 6 was dissolved into 1,254 g of methanol containing 12%
of water under warming at 40.degree. C. and then cooled to
-5.degree. C. with stirring over 5 hours to obtain 350 g of a
crystal through filtration. This crystal was added with 1,230 of an
aqueous solution of 3% hydrochloric acid, which was subjected to an
acid decomposition with stirring at 90.degree. C. for 2 hours. The
resulting oleic acid layer was fully washed with an aqueous
solution of 0.5% malic acid and dehydrated to obtain 318 g of a
highly purified oleic acid (E).
EXAMPLE 8
Each of the highly purified oleic acids of Examples 6 and 7 was
added with 3% of silica gel, stirred at 40.degree. C. under
nitrogen gas atmosphere for 1 hour and filtered to obtain each of
more highly purified oleic acids (D1) and (E1).
EXAMPLE 9
Each of the highly purified oleic acids of Examples 6 and 7 was
distilled in the same manner as in Example 5 to obtain each of more
highly purified oleic acids (D2) and (E2).
The compositions and quality characteristics of the highly purified
oleic acids obtained in Examples 6-9 according to the present
invention are shown in the following Table 2.
TABLE 2
__________________________________________________________________________
Present invention Fatty acids in filtrate Teaseed oil after urea
Example 6 Example 7 Example 8 Example 9 Test item fatty acid
separation (D) (E) (D1) (E1) (D2) (E2)
__________________________________________________________________________
1 Composi- C.sub.16:0 8.5 0.3 0.1 0.1 tion of C.sub.16:1 0.1 0.2
fatty C.sub.18:0 2.6 acids (%) C.sub.18:1 81.7 86.9 98.9 99.6 99.0
99.6 99.3 99.9 cis-.omega.9 C.sub.18:2 6.5 11.6 1.0 0.4 0.9 0.4 0.7
0.1 C.sub.18:3 0.5 0.9 C.sub.20:0 0.1 C.sub.20:1 0.1 2 Carbonyl
value 10.3 0.9 0.4 0.7 0.3 0.2 0.1 (meq/kg) 3 Odor intensity 8 2 1
1 0-1 0 0 4 Original color 400 40 20 15 10 10 5 (APHA) 5 Heat color
.gtoreq.500 100 70 50 30 20 5 stability (APHA) 6 Thermal oxida-
.gtoreq.500 120 90 90 60 60 30 tion color stability (APHA) 7 Base
color .gtoreq.500 140 100 110 80 70 40 stability (APHA) 8 Acid
color .gtoreq.500 180 120 140 90 90 60 stability (APHA) 9 Oxidation
16.7 0.2 0 0.1 0 0 0 stability (POV)
__________________________________________________________________________
EXAMPLE 10
After 1,060 g of urea was added and dissolved into 3,000 g of
methanol under warming at 60.degree. C., 1,000 g of olive oil fatty
acids warmed at 60.degree. C. was added and dissolved thereinto.
Then, the resulting solution was cooled from 60.degree. C. to
15.degree. C. with stirring over 4 hours, and the resulting
precipitated crystal was filtered off. The thus obtained filtrate
was added and dissolved into 750 g of urea at 50.degree. C., and
then cooled to 10.degree. C. with stirring, and the resulting
precipitated crystal was again filtered off to obtain 3,488 g of a
filtrate (content of fatty acid: 447 g, acid value: 192.8 g,
content of urea: 158 g). This filtrate was added with 372 g of an
aqueous solution containing 38.8 g of potassium hydroxide
(corresponding to 45% of the equivalent of the contained fatty
acid) at 40.degree. C. and then cooled to -10.degree. C. with
stirring over 6 hours to obtain 342 g of a crystal of the acid salt
of oleic acid (content of acid salt: 289 g) through fitration. This
crystal was added with 1,894 g of an aqueous solution of 10% citric
acid, which was subjected to an acid decomposition with stirring at
90.degree. C. for 2 hours. The resulting oleic acid layer was fully
washed with an aqueous solution of 0.5% tartaric acid and
dehydrated to obtain 278 g of a highly purified oleic acid (F).
EXAMPLE 11
The acid salt crystal of oleic acid obtained in the same manner as
in Example 10 was dissolved into 1,026 g of acetone containing 8%
of water under warming at 50.degree. C. and then cooled to
-2.degree. C. with stirring over 5 hours to obtain 276 g of a
crystal through filtration. This crystal was added with 1,716 g of
an aqueous solution of 10% citric acid, which was subjected to an
acid decomposition with stirring at 90.degree. C. for 2 hours. The
resulting oleic acid layer was well washed with an aqueous solution
of 0.5% tartaric acid and dehydrated to obtain 252 g of a highly
purified oleic acid (G).
EXAMPLE 12
Each of the highly purified oleic acids obtained in Examples 10 and
11 was added with 2% of activated clay, stirred at 40.degree. C.
under nitrogen gas atmosphere for 30 minutes, and filtered to
obtain each of more highly purified oleic acids (F1) and (G1).
EXAMPLE 13
Each of the highly purified oleic acids obtained in Examples 10 and
11 was distilled in the same manner as in Example 5 to obtain each
of more highly purified oleic acids (F2) and (G2).
The compositions and quality characteristics of the highly purified
oleic acids obtained in Examples 10-13 are shown in the following
Table 3.
TABLE 3
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Present invention Fatty acids in filtrate after Olive oil two times
of Example 10 Example 11 Example 12 Example 13 Test item fatty
acids urea separation (F) (G) (F1) (G1) (F2) (G2)
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1 Composi- C.sub.16:0 10.4 0.4 0.1 0.1 tion of C.sub.16:1 0.7 1.4
fatty C.sub.18:0 3.1 acids (%) C.sub.18:1 77.2 81.4 98.7 99.5 98.7
99.5 99.1 99.8 cis-.omega.9 C.sub.18:2 7.4 14.9 1.2 0.5 1.2 0.5 0.9
0.2 C.sub.18:3 0.9 1.8 C.sub.20:0 0.3 2 Carboxyl value 7.2 0.8 0.4
0.7 0.3 0.1 0 (meq/kg) 3 Odor intensity 6 1-2 1 1 0-1 0 0 4
Original color 350 40 20 10 5 10 5 (APHA) 5 Heat color .gtoreq.500
110 80 40 15 20 5 stability (APHA) 6 Thermal oxida- .gtoreq.500 120
90 80 60 50 30 tion color stability (APHA) 7 Base color .gtoreq.500
140 110 110 80 70 50 stability (APHA) 8 Acid color .gtoreq.500 170
120 120 90 80 60 stability (APHA) 9 Oxidation 17.2 0.2 0 0.2 0 0 0
stability (POV)
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As apparent from the above results, fatty acids other than oleic
acid and minor impurities contained in the starting fatty acid
mixture can almost completely be removed according to the
invention. Furthermore, the highly purified oleic acid according to
the invention has a purity of approximately 100%, so that it is
colorless and odorless and has excellent heat, oxidation and
chemical stability as well as being safe to cutaneous health.
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